This invention relates to a snow ski and has application to alpine skis, cross-country skis, snowboards and the like. More particularly, the snow ski of this invention is of the type which is made from separately constructed and joined together upper and lower elongate ski sections wherein the lower surface of the upper ski section overlies the top surface of the lower ski section between the ski tip and ski tail which is on the lower ski section.
An early example of skis employing separately constructed but joined together upper and lower ski sections is disclosed in U.S. Pat. No. 2,258,046 issued Oct. 7, 1941--Clement. As disclosed by Element, the elongate upper ski section, described as a reinforcing member, in the ski boot location or attachment area, is fixedly attached to the underlying lower ski section in the same area. That portion of the upper ski section forwardly and rearwardly of the boot fixation area, proximate its two free ends, is secured to the top surface of the lower ski section by means of arched clips attached to the top surface of the lower ski section so as to permit the relatively narrow free ends of the upper ski section, which extend through the clips, to undergo longitudinal sliding movement relative to the underlying lower ski section during longitudinal flexing of the ski.
More recently, Le Masson et al in U.S. Pat. Nos. 5,392,086 and 5,447,322 respectively issued on Feb. 28, 1995 and Sep. 5, 1995 have disclosed a number of different ski designs or configurations involving an upper ski section or "stiffener", which in U.S. Pat. No. 5,447,322 is disclosed as being attached to the underlying lower ski section or "beam" positively by a flexible interface constituted by a film of an elastic or viscose elastic material and/or a rigid connection which does not extend beneath the entire lower surface of the stiffener, and which in U.S. Pat. No. 5,393,086 discloses that the overlying stiffener is only attached at its front and rear ends to the lower ski section or base and that the fixation location for the ski boot is located above and not attached to the stiffener. Like Element, and as disclosed in the Le Masson et al references, the lower ski section, in side profile, is thicker in its medial area and is cambered along its longitudinal length. As a result, the lower surface of the associated upper ski section is shaped to match.
Both the upper reinforcing member as disclosed by Element and the "stiffener" of Le Masson et al are primarily intended to impart to the snow ski greater resistance to longitudinal flex. Their contribution to resisting torsional twisting of the snow ski is less significant, as the ski's ability to resist lateral twisting, particularly in the areas of the ski in front of and behind the ski boot fixation area, to a significant extent, is dictated by how the lower ski section or "beam" is constructed with this consideration in mind. Indeed, in U.S. Pat. Nos. 5,392,086 and 5,447,322 it is indicated the rigidity of the stiffener is less or only equal to that of the lower ski section or base.